Usopp's name is derived from the Japanese word "Uso" which means lie or falsehood (1). The elongated nose is an allusion to Pinocchio.
Franky was actually created with seiyu Kazuki Yao in mind after the manga-ka heard the voice actor's performance as Jango and Bon Clay, however it is likely that Franky is based on Pop-eye. In addition to the enlarged forearms, both characters are 34 and both rely on food for energy and powers (Popeye uses spinach and Franky uses cola) (2).